1. Field of the Invention
Non-phosphorus containing builders for detergent compositions.
2. Description of the Prior Art
In recent years the problems of eutrophication which can be defined as a slow rate, natural process of enrichment of waters with nutrients, such as phosphorus and nitrogen has received much notoriety. Uncontrolled or pronounced eutrophication has been found to cause incresed algal growth and algal scums which not only are unaesthetic, odorous, distasteful and clog filters of treatment plants but also create disproportionate demands on the available oxygen in the water. It has been postulated that in several bodies of water various human activities have contributed to acceleration of the process through such factors as inordinate enrichment of natural runoff, ground water and agricultural drainage, sewage and waste effluents. It has also been suggested that the phosphorus-containing builders present in detergent compositions can be a contributing factor in eutrophication, and therefore any substitutes which do not contain phosphorus may decrease to some extent the eutrophication problem. Thus, those skilled in the art have expended a great deal of time and money to solve this problem and find suitable materials to reduce or replace the existing phosphate builders in detergent compositions. This work is still continuing since most of the builders discovered to data have been deemed unsatisfactory for a variety of reasons and are most often less efficient than the existing phosphate builders.
Salts of oxydiacetic acid, also known as diglycolic acid, are known in the art, their use as builder compounds for detergent compositions being disclosed in copending application Ser. No. 708,610, filed Feb. 27, 1968 in the name of Vincent Lamberti. While these compounds provide excellent building characteristics and are well suited for their intended use, a consistent effort has been placed on making them even more suitable and desirable as possible phosphate replacements.
In this regard the present inventors have made the unexpected discovery that when the configuration of the molecule is altered such as when certain groups are substituted onto the .alpha. and/or .alpha.' positions of the oxydiacetate molecule or when the .alpha. and .alpha.' carbon atoms are joined together to form a heterocylic ring the toxicity of the resultant compound is surprisingly and dramatically reduced. Many phosphate builder compounds, e.g., trisodium polyphosphate, have emetic properties, i.e., they cause spontaneous regurgitation if they are accidentally swallowed, and thus are considered as relatively safe in the household environment. Many of the potential phosphate replacements, unfortunately, do not possess this characteristic so that the toxicity of the compound becomes an exceedingly important factor in the choice of a possible replacement-- the assumption having to be made that small children are prone to ingest anything within their reach, including detergent compositions. In point of fact there are several thousand reported cases a year of household cleanser ingestions. Thus, if a particular compound can be found which demonstrates both good detergency building characteristics and which can be classified as non-toxic, a substantial step forward will have been made toward the goal of an acceptable non-phosphorus containing builder.